Eutychius (18), St., patriarch of Constantinople. His biography, composed by his chaplain Eustathius, has been preserved entire. Eutychius was born at Theium in Phrygia c. 512. His father Alexander was a general under Belisarius. Eutychius took the monastic habit at Amasea at the age of 30, c. 542.

As an archimandrite at Constantinople he stood high in favour with the patriarch Mennas, at whose death in 552 he was nominated by Justinian to the vacant chair.

At the beginning of 553 Eutychius wrote to pope Vigilius, making his profession of the Catholic faith, declaring his acceptance of the four councils and the letters of St. Leo, and requesting Vigilius to preside over the council that was to be held on the question of the Three Chapters. Vigilius refused, and Eutychius shared the first place in the assembly with the patriarchs Apollinarius of Alexandria and Domninus of Antioch. At the second session the pope excused himself again, on the ground of ill-health. The subscription of Eutychius to the Acts of this synod, which sat from May 5 to June 2, 553, is a summary of the decrees against the Three Chapters.

Eutychius came into violent collision with Justinian in 564, when the emperor adopted the tenets of the Aphthartodocetae. Eutychius, in a long address, demonstrated the incompatibility of that theory with Scripture; but Justinian insisted on his subscribing to it, and finding him uncompromising, ordered his arrest. On Jan. 22, 565, Eutychius was at the holy table celebrating the feast-day of St. Timotheus in the church adjoining the Hormisdas palace (cf. du Cange, Cpolis. Chr. lib. ii. p. 96, lib. iv. p. 93, ed. 1729), when soldiers broke into the patriarchal residence, entered the church, and carried the patriarch away, first to a monastery called Choracudis, and the next day to that of St. Osias near Chalcedon. The 8th day after this outrage Justinian called an assembly of princes and prelates, to which he summoned Eutychius. The charges against him were trifling and absurd: that he used ointments, ate delicate meats, and prayed long. Cited thrice, Eutychius replied that he would only come if he were to be judged canonically, in his own dignity, and in command of his clergy. Condemned by default, he was sent to an island in the Propontis named Principus, and afterwards to his old monastery at Amasea, where he spent 12 years and 5 months. On the death of Joannes Scholasticus, whom Justinian had put in the patriarchal chair, the people of Constantinople loudly demanded the return of Eutychius. Justin II. had succeeded Justinian, and had associated with himself the young Tiberius. The emperors immediately sent an honourable deputation to Amasea to bring back Eutychius, who returned with great joy to Constantinople in Oct. 577. An immense concourse met him, shouting aloud, "Blessed is he that cometh in the name of the Lord," and "Glory to God in the highest, on earth peace." In questionable imitation of our Lord he entered on an ass's colt, over garments spread on the ground, the crowd carrying palms, dancing, and singing. The whole city was illuminated, public banquets were held, new buildings inaugurated. Next day he was met by the two emperors with conspicuous honour at the church of the Virgin in Blachernae. He then proceeded to the great church, which was filled from end to end, mounted the pulpit, and blessed the multitude. He was six hours distributing the communion, as all wished to receive from his own hands.

Towards the end of his life Eutychius maintained that after the resurrection the body will be more subtle than air, and no longer palpable. Gregory the Great, then residing at Constantinople as delegate of the Roman church, felt himself bound to oppose this opinion. The emperor Tiberius talked to the disputants separately, and tried to reconcile them; but the breach was persistent. Eutychius breathed his last quietly on Sunday after Easter Day, Apr. 5, 582, aged 70 years. Some of his friends told Gregory that, a few minutes before his end, he touched the skin of his hand, saying, "I confess that in this flesh we shall rise again" (Paul. Diac. Vit. Greg. Mag. lib. i. capp. 9, 27-30; Vit. Greg.

The chronology of his life here followed is that fixed by Henschen in his introductory argument to the Life by Eustathius (Boll. Acta SS. 6 Ap. i. 550). His literary remains are his letter to pope Vigilius already mentioned, printed in Greek and Latin by Mansi (ix. 186), and by Migne (Patr. Lat. lxix. 63; Patr. Gk. lxxxvi. 2401), and some fragments of a Discourse on Easter and the Holy Eucharist (Migne, Patr. Gk. lxxxvi. 2391). In this treatise Eutychius argues against the Quartodecimans, against the Hydroparastatae who use water instead of wine at communion (he says that the only apostolic tradition is the mixture of both), against certain schismatic Armenians who used only wine, and against some Greeks and Armenians who adored the elements as soon as they were offered and before consecration. The lost work of Eutychius was a discourse on the manner of existence of reasonable natures in space, a sort of physical theory of the future life. Patr. Gk. lxxxix. §§ 2270-2389; Bolland. AA. SS. Ap. i. 548; ib. App. p. lix. in Greek; Surius, de Prob. Hist. SS. Apr. p. 82 ; Evagr. iv. 37; Theoph. Chronogr. 193, 201, 202, 203, 210, 211, 212, 213; Cave, i. 527.